1. Field of the Invention
The present invention relates to an electro-magnetic type fuel injection valve for an internal combustion engine and, more particularly, relates to a fuel injection valve which includes an injector body having a single fuel injection hole and an adapter having a plurality of injected fuel paths for injecting the fuel injected through the fuel injection hole into an intake path of the engine.
2. Description of the Related Art
Japanese Patent Publication SHO No. 60-204962 and Japanese Utility Model Publication SHO No. 61-160266 disclose a fuel injection valve having three injected fuel paths. The prior art fuel injection valve includes an injector body and an adapter fixed to the injector body. The injector body includes a single fuel injection hole for metering fuel to be injected and the adapter includes a concave portion for defining a dead volume portion into which the fuel injected through the fuel injection hole is injected and three injected fuel paths which extend through the adapter and open to the dead volume portion. The concave portion has a flat bottom surface perpendicular to an axis of the adapter, and the three injected fuel paths open to the dead volume portion at the bottom surface of the concave portion. The fuel injected through the fuel injection hole into the dead volume portion forms a pillar-like pattern of injected fuel at the dead volume portion and flows toward the bottom surface of the concave portion. When the fuel collides with the bottom surface of the concave portion, the fuel changes its flow direction from a direction along the axis of the adapter to a direction along the bottom surface of the concave portion which is substantially perpendicular to the axis of the adapter. As a result, a large portion of the fuel attaches to either the bottom surface and the side surface of the concave portion or the inside surfaces of the injected fuel paths and momentarily collects on the surfaces. When the collecting fuel increases in amount and the weight of the collecting fuel finally exceeds the surface tension of the collecting fuel, the collecting fuel begins to move downward along the surfaces and is injected from the injected fuel paths into the intake port of the engine together with a fuel which is injected at successive injection timings. When the fuel is collecting on the surfaces of the concave portion and the injected fuel paths, the air-fuel ratio of the engine becomes greater than the specified value and the fuel-mixed gas of the engine becomes lean, while when the collecting fuel is released from the surfaces and flows into the intake port of the engine, the fuel-mixed gas of the engine becomes rich. Thus, the collecting fuel makes the response characteristic of the engine unstable. Further, because the collecting fuel flows into the intake port of the engine in the form of lumps which are not sufficiently atomized or broken into pieces, the fuel in the form of lumps deteriorates combustion characteristics of the engine. Thus, it is desired to minimize the attachment of the fuel onto the surfaces of the concave portion and the injected fuel paths.